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Abstract

The Curve Number (CN) method is widely used to estimate runoff volumes, flood hydrographs, maximum flows, as well as an input for hydrological models, representing the interaction between soil and water. We developed a consistent and validated, gridded dataset for Chile, CN30-CL, based on the methodology proposed by Jaafar (GCN250), defining CN at 30 m spatial resolution based on a National Land Cover published in 2014 and the hydrologic soil group global data product (HYSOGs250m) released by 2018. CN30-CL was validated against CN estimates from previous national studies performed at 34 basins, where precipitation and flow records were used to estimate CN for these precipitation events. The validation process shows a good performance for Central and South Chile, presenting some differences for basins located in the Northern part of the country (arid basins). The curve numbers obtained with CN30-CL agree with the estimates of previous studies (based on records), concluding that this product delivers reasonable values. This database allows to study the effect of the heterogeneity of the CN values over a basin, as well as, for example, to explore the dependency between CN and snow line (that defines rainfall contributing area in snow driven basins) or study the impact on runoff linked to a possible change in the type of land cover, which can be related to fires, increasing aridity, anthropic action, climate change, among others. The methodology applied is flexible and easily adaptable, providing a new database that serves as a reference for consultants and researchers.